Apparatus for monitoring and controlling tension in an advancing flexible elongate material

ABSTRACT

An apparatus for detecting and regulating tension in a textile rope being pulled in a path from a source through a tension adjusting means by an advancing means includes a beam pivotally mounted for angular movement about an axis transverse to the beam and a guide arrangement to direct the rope through the beam pivot axis. One guide of the arrangement is carried by the beam at a location downstream of the pivot axis, the other being located upstream of the pivot axis. Passing the rope through the axis nullifies the effect of changes in frictional properties of the rope on tension induced deflection of the beam. Means are provided for detecting the amount of said angular movement of the beam and transducing it into a signal to actuate a control means for operating the tension adjusting means.

Seney Dec. ill, 1973 APPARATUS FOR MONITORING AND CONTROLLING TENSION IN AN ADVANCING FLEXIBLE ELONGATE MATERIAL ,lohn Seymour Seney, Seaford, Del.

Assignee: E. I. du Pont de Nemours and Company, Wilmington, Del.

Filed: Feb. 25, 1972 Appl. No.: 229,456

Inventor:

References Cited UNITED STATES PATENTS 1/1965 Robertson 226/25 UX 9/1967 Bancroft 307/119 5/1968 Helms... 226/195 X l/197l Ferguson 226/195 Primary Examiner-Allen N. Knowles Att0rneyl loward P. West, Jr.

[57] ABSTRACT An apparatus for detecting and regulating tension in a textile rope being pulled in a path from a source through a tension adjusting means by an advancing means includes a beam pivotally mounted for angular movement about an axis transverse to the beam and a guide arrangement to direct the rope through the beam pivot axis. One guide of the arrangement is carried by the beam at a location. downstream of the pivot axis, the other being located upstream of the pivot axis. Passing the rope through the axis nullifies the effect of changes in frictional properties of the rope on tension induced deflection of the beam. Means are provided for detecting the amount of said angular movement of the beam and transducing it into a signal to actuate a control means for operating the tension adjusting means.

4 Claims, 4 Drawing Figures TO AIR SUPPLY .mmmmmma- 3.777, 959

snmzorz APPARATUS FOR MONITORING AND CONTROLLING TENSION IN AN ADVANCING FLEXIBLE ELONGATE MATERIAL BACKGROUND OF THE INVENTION This invention concerns apparatus for the measurement and regulation of dynamic tension in moving flexible elongate structures such as textile yarns or ropes. More specifically, it relates to tension monitors that compensate for the effects of. speed and friction variability between the monitor and the moving material.

Many different devices are shown in the art for detecting and holding the tension constant in a running flexible element. Many of such devices employ a force triangle type of tension measuring principle wherein two fixed guides or rolls are mounted at two corners of an equilateral or isosceles triangle with a third guide or roll at the apex. This third roll is held in place by a mechanical forcing means arranged so that the force can be measured. The flexible element is passed around the three guides or rolls in such a manner that tension tends to force the apex toward the base. The force required to hold the movable roll in place or the displacement of the movable roll against a calibrated load measures the tension in the running flexible element. One particular device, as disclosed by Seney in U. S. Pat. No. 2,767,576, employs a pivotably balanced beam arrangement to monitor the force on the third (apex) guide or roll. In another arrangement, as disclosed by Ferguson in U. S. Pat. No. 3,556,369, tension in a strand is monitored by way of the torque exerted by the strand when it is passed in an S-shaped path over two guides mounted at opposite ends of a diameter of a disc, or ends of a bar, rotatable about a fixed pivot at the center of the disc or bar.

All of these prior art devices have served satisfactorily to measure tension and/or provide feedback for tension regulation under some conditions. However, when highly precise tension regulation or measurement is needed or where the frictional properties of the yarn against the detector vary considerably, the prior art devices are often not acceptable.

SUMMARY OF THE INVENTION An apparatus for detecting and regulating tension in a flexible elongate structure advancing in a path from a source through a tension adjusting means and a first guide means to an advancing means for the structure. The apparatus comprises a beam located between the first guide means and the advancing means and pivotally mounted at one location for angular movement about an axis transverse to the beam. The beam carries a second guide means spaced from said one location, the first and second guide means direct the structure in a path through the transverse axis. Means for measur' ing the amount of said angular movement and transducing said movement into signals are coupled to a control system whereby the signals actuate the control system which operates the tension adjusting means. The tension is regulated to an extent required to null the angular movement of the beam.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional elevation view of a textile rope ball warper tension regulating system with associated schematic pneumatic circuit diagram.

FIG. 2 is a perspective partial view of the tension transducer mounting arrangement for the apparatus of FIG. 1.

FIG. 3 is a beam balance tension transducer for high speed yarn tension regulation.

FIG. 4 is a vernier servo feed roll speedregulator in perspective.

Turning first to FIGS. 1 and 2, the invention is described in the form of apparatus arranged to provide accurate tension regulation for a textile rope ball warper. A textile rope R is received from a creel supply not shown and introduced over one or more servo controlled tension adjusters 10. These adjusters or tension regulating means comprise two parallel tension bars 11, ll mounted in end plates 12 which are journalled about axis 14 for rotation by action of a pneumatic servo system 20, i.e., control means, through mechanical linkage 22. A guide roll 24, Le, a first guide means, is journalled to roll mounting which in turn is fixed to tension transducer frame 26. Frame 26 has off-set portion 27 arranged to provide room for elongated tension transducer beam 28 pivotally mounted at one end for rotational movement above the lower portion of frame 26 and about an axis A, A transverse to the beam by means of two beam flexure pivots 30. Pivots 30 are made of materials such as thin spring steel or Beryllium copper. They are spaced toward each end of the frame and beam so that a vertical passageway 32 is available for passage of rope R from the exit edge of roll 24 vertically upward to eyelet guides 34, i.e., second guide means, which are placed in appropriate holes through beam 28 above pivots 30 and structured so that the rope R, in passing from roll 24 to contact guides 34 at surface 35, must pass vertically upward through the line of the transverse axis A, A (FIG. 2) of flexure pivots 30. An advancing means or winding mechanism, e.g., the ball warper (not shown) is located so that rope R must pass through eyelets 34 in a substantially horizontal direction. Frame off-set portion 27 is further extended upward, across and partly downward to form an upper cap portion 36 of the frame adjacent to and surrounding the top portion of beam 28. A set point pneumatic bellows 40 is attached near the lower left end of cap portion 36 and aligned near the upper end of beam 28 so that finger 41 of the bellows 40 can exert a preset force on beam 28 near its upper end. A pneumatic line 42 extends back from bellows 40 past bleed valve 44, gage 46, and thence to regulator valve 48. Line receives air from a pressure source not shown to supply valve 48. An elongated bolt 54 is threaded to the upper end of beam 28 in a position to receive finger 41 and tightened in place by means of nut 55. The bolt extends to the right of beam 28 through a hole 56 in frame portion 27. Nuts 58, 58 are threaded onto bolt 54 to provide mechanical limiting arrangement for the movement of beam 28. A beam deflection indicator control valve 60 is attached to the inside of cap 36 just above bellows 40. A zero adjusting screw 62 is threaded to the upper part of beam 28 in a position to engage the actuating end of valve 60. Lock nut 63 is positioned on screw 62 in order to lock this screw in position after zero adjustment. Pneumatic line 64 extends from valve 60 to rate control valve 66 and line 68 extends from valve 66 to a second rate control valve 70. A branch line 72 from line 68 connects to solenoid actuated stand-by valve 76 after passing gage 74. Line 78 extends from valve 76 to pneumatic servo system 20, thus completing one part of the pneumatic circuit. In the preferred embodiment, system 20 is a Conoflow Corporation (Blackwood, NJ.) pneumatic servo type EB-S l-XB-C. Another pneumatic line 80 extends from valve 70 past gage 84 to air pressure regulator 82 and thence over line 86 to supply of pressurized air not shown. Another pneumatic line 87 extends from the air supply to a second regulator 88, past gage 90 to control valve 92 and over line 94 to pneumatic system 20.

In operation, textile rope R is threaded in an exaggerated S-shape path around rods 11 and 11 of tension adjuster 10, or a series of such adjusters, and thence around guide roll 24. From roll 24, the rope passes vertically upward through passageway 32 in line with axis A, A and thence around eyelet guide 34 and thereby through the tension transducer beam 28. Rope R is then drawn off by a ball warper and made into a ball warped package of rope. The warper is not shown since it is of conventional structure. The tension transducer produces a proportional signal of -15 lbs. which proportionally controls rope tension through the servo system 20 by adjusting rotation of the tension adjuster bar end plates 12 between zero and full effectiveness of bars 11, 11'. The tension set point is manually adjusted by means of air pressure regulator valve 48 by setting the pressure on bellows 40 as read by gage 46. Bleed valve 44 protects against pressure buildup caused by any leakage that might occur in regulator 48. Air pressure to beam deflection control valve 60 is set at lbs. by means of regulator 82 and flows through flow rate control valves 70 and 66 to the control valve 60.

Flow valve 66 is set to allow air pressure to build up to 15 lbs. on gage 74 during a time interval of 2 minutes whenever control valve 60 is closed. This occurs when tension in rope R is below set point and bellows 40 through finger 41 holds beam 28 away from actuating valve 60. However, if valve 60 is opened, flow valve 66 allows pressure, as indicated by gage 74, to drop to 2 lbs. in a time interval of 2 minutes. Valve 60 is opened when the tension in rope R is sufficient to force beam 28 against the pressure of bellows 40 to an extent necessary to open valve 60.

Servo system is arranged so that, as air pressure coming in over line 78 builds up due to valve 60 being closed by low rope tension, the tension adjuster 10 is caused to rotate in a direction to increase the snubbing action on the rope. This raises the tension until a balance of torque is reached between that caused by tension in the rope passing through eyelets 34 and the force of the set point bellows 40. When tension becomes too high, the reverse action occurs.

Solenoid operated valve 76 is provided to be closed by an electrical signal when the ball warper is shut down. This holds the air in line 78 at the normal running pressure at the time of shut down. An electrical time delay relay holds valve 76 closed for a controlled period of time after startup so that the ball warper may reach operating speed before the tension regulator is allowed to start operation. This action minimizes tension surges during startup.

The level of damping action in servo system 20 is adjusted by means of regulator 88 and flow valve 92 to obtain the predetermined required pressure as indicated by gage 90.

The most significant ope rational advantage of this invention lies in its ability to regulate the tension in a rope at the output end of the device in spite of radical changes in the frictional properties of the rope as it is received and, therefore, enable formation of uniform wound packages. This is accomplished through the fact that changes in friction of the rope against the eyelets 34 and around bars 11, 11' are immediately detected by the tension detector which is sensitive only to changes in the tension in that part of the rope as it leaves the detector. The tension in the vertical portion of rope between guide 24 and eyelet 35 exerts no torque on beam 28 and hence has no influence on the tension detector. This leaves the detection exclusively confined to tension in the output rope end. Thus, windup tension is maintained constant in spite of wide variations in frictional properties or in speed.

Another embodiment of this invention is shown by FIGS. 3 and 4. It takes the form ofa yarn tension regulator employing a horizontal tension transducer beam and a Vernier speed adjusting system for the yarn feed roll. Speed adjusting is actuated from a photoelectric beam balance detector and speed control circuit. Thus. input yarn Y, is brought into the tension regulator from feed roll 100. Thence, it passes through the pivot axis of tension transducer beam 102 which is the line of the knife-edge of support 104. Next, the yarn passes over pin guide 106 and then, as output yarn Y,,, to takeup rolls not shown. Tension in Y is regulated by this apparatus in spite of variations in yarn to guide friction.

In this embodiment, beam 102 is counterbalanced by a set point counterbalancing weight 108 near one end of the beam opposite the end at which pin guide 106 is located. An extension 109 to one end of beam 102 has a hole 110 located therein to provide for passage of light from lamp and lens system 111 to photocell 112, both of which are fixed in space. Signals from photocell 112 are passed over cable 113 to speed control system 114 which is mechanically linked over means 116 to feed roll 100.

Roll 100 is mounted on shaft 122 and rotated by primary drive motor 120. Motor is an AC synchronous motor. It receives its power over cable 124 through slip ring arrangement 126. The frame of motor 120 is mounted for rotation in bearing arrangement 128, 128. Slip ring system 126 is mounted on shaft 130 which is attached to the frame of motor 120 and rotates therewith. At the outer end of shaft 130 there is located a large gear 132 which meshes with gear 134. This latter gear 134 is mounted on shaft 136 of secondary (vernier speed adjusting) motor 138. Cable is connected to the electrical circuit portion of speed control system 114 of FIG. 3. Motor 138 and gears 134, 132 provide the linkage 116 indicated by the dashed line (FIG. 3).

In operation, as before, when the tension in the output yarn Y exceeds the set point as determined by weight 108 the beam 102 is depressed so that the signal from photocell 112 over cable 113 causes the speed control system 114 to appropriately and proportionally adjust the speed of roll 100 thus bringing the tension back to the proper level. This speed adjustment is accomplished by action of motor 138 by changing the rate and/or direction of rotation of the frame of primary motor 120.

Here again, by the principle of locating the exit tangent of roll 100 such that the yarn passes through the axis of rotation of beam 102 and thence to guide 106, true tension can be regulated in the output yarn line Y in spite of variations in friction between the yarn and guide pin 106. This enables very precise regulation of the tension in the output end of the yarn Y The invention has been described by way of two specific embodiments. It will be evident to one skilled in the art that the particular designs of the pivotable tensioning transducer beam, the means for providing set point counter-balancing torque and the means for detecting and transducing movement of the beam to provide feedback signals to adjust the input tension are matters of variable design choice. Thus, many variations will be apparent to those skilled in the art and although illustrated in terms of monitoring tension in textile yarn or rope, this invention is generally applicable to moving flexible elongated structures such as wire, cable, screen and fabric.

What is claimed is:

1. An apparatus for detecting and regulating tension in a flexible elongate structure moving in a path from a source through a tension adjusting means and a first guide means to an advancing means for the structure, said apparatus comprising: a beam pivotally mounted at a location between its ends for angular movement about an axis transverse to said beam, said beam carrying a second guide means spaced from said location, said beam being located between and mechanically separate from said first guide means and said advancing means, said first and said second guide means directing said structure through said axis whereby the tension in said structure upstream of said second guide exerts no torque on said beam, means for detecting the amount of said angular movement and transducing said amount into a signal; and a control means for actuating said tension adjusting means, said signal being fed to said control means for actuation thereof.

2. The apparatus as defined in claim 1, said second guide means being an eyelet having an opening through which said structure passes, said opening having a central axis in a plane perpendicular to said transverse axis.

3. The apparatus as defined in claim 1, including means for limiting said angular movement of the beam.

4. The apparatus as defined in claim 1, said flexible structure being a textile rope. 

1. An apparatus for detecting and regulating tension in a flexible elongate structure moving in a path from a source through a tension adjusting means and a first guide means to an advancing means for the structure, said apparatus comprising: a beam pivotally mounted at a location between its ends for angular movement about an axis transverse to said beam, said beam carrying a second guide means spaced from said location, said beam being located between and mechanically separate from said first guide means and said advancing means, said first and said second guide means directing said structure through said axis whereby the tension in said structure upstream of said second guide exerts no torque on said beam, means for detecting the amount of said angular movement and transducing said amount into a signal; and a control means for actuating said tension adjusting means, said signal being fed to said control means for actuation thereof.
 2. The apparatus as defined in claim 1, said second guide means being an eyelet having an opening through which said structure passes, said opening having a central axis in a plane perpendicular to said transverse axis.
 3. The apparatus as defined in claim 1, including means for limiting said angular movement of the beam.
 4. The apparatus as defined in claim 1, said flexible structure being a textile rope. 